Structure of the yeast spliceosomal postcatalytic P complex.
The spliceosome undergoes dramatic changes in a splicing cycle. Structures of B, Bact, C, C*, and intron lariat spliceosome complexes revealed mechanisms of 5'-splice site (ss) recognition, branching, and intron release, but lacked information on 3'-ss recognition, exon ligation, and exon release. Here we report a cryo-electron microscopy structure of ... the postcatalytic P complex at 3.3-angstrom resolution, revealing that the 3' ss is mainly recognized through non-Watson-Crick base pairing with the 5' ss and branch point. Furthermore, one or more unidentified proteins become stably associated with the P complex, securing the 3' exon and potentially regulating activity of the helicase Prp22. Prp22 binds nucleotides 15 to 21 in the 3' exon, enabling it to pull the intron-exon or ligated exons in a 3' to 5' direction to achieve 3'-ss proofreading or exon release, respectively.
Mesh Terms:
Base Pairing, Biocatalysis, Catalytic Domain, Cryoelectron Microscopy, DEAD-box RNA Helicases, Exons, Introns, Multienzyme Complexes, Mutation, Protein Conformation, RNA Splice Sites, RNA Splicing, RNA Splicing Factors, Ribonucleoprotein, U4-U6 Small Nuclear, Ribonucleoprotein, U5 Small Nuclear, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spliceosomes
Base Pairing, Biocatalysis, Catalytic Domain, Cryoelectron Microscopy, DEAD-box RNA Helicases, Exons, Introns, Multienzyme Complexes, Mutation, Protein Conformation, RNA Splice Sites, RNA Splicing, RNA Splicing Factors, Ribonucleoprotein, U4-U6 Small Nuclear, Ribonucleoprotein, U5 Small Nuclear, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spliceosomes
Science
Date: Dec. 08, 2016
PubMed ID: 29146870
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